Waldenstrom’s macroglobulinemia (mak-roe-glob-u-lih-NEE-me-uh) is a rare type of blood cancer that begins in the white blood cells.

Waldenstrom Macroglobulinemia (WM) is a rare, slow-growing cancer of the lymphatic system. Cancers of the lymphatic system are called lymphomas. To understand WM, it’s helpful to know some basic information about your body’s lymphatic system and the function of lymphoid tissue.

What is the lymphatic system?

The lymphatic system is made up of a large network of vessels, organs, and tissues that help your body fight disease and infection. Lymphoid tissue can be found in many places in the body, including:

  • Lymph nodes – small, bean-shaped glands located throughout your body. Some are found in clusters in places like your underarm area, the sides of your neck, your groin, abdomen and chest.

  • Certain organs – such as your spleen, tonsils and adenoids.

  • Bone marrow – the soft, spongy tissue in the center of most bones. This is where new blood cells are made.

There are three types of blood cells:

  • Red blood cells, called erythrocytes, carry oxygen throughout the body.

  • Platelets, called thrombocytes, form blood clots to stop bleeding and help with wound healing.

  • White blood cells, called lymphocytes, help the body fight infection and disease.

Lymphoid tissue is made mostly of white blood cells, or lymphocytes. There are two main types of lymphocytes: B lymphocytes (B cells) and T lymphocytes (T cells). Normally, B cells help your body fight infection by turning into plasma cells. It’s the job of plasma cells to make antibodies – also called immunoglobulins or Ig for short – the proteins that help your body protect itself against infection and other types of threats. There are five main types of antibodies, known as IgA, IgD, IgE, IgG, and IgM.

How does WM affect the lymphatic system?

WM is a cancer that starts in your B cells. When a person has WM, there is a change, or mutation, to their B cells resulting in the production of an abnormal lymphocyte-plasma hybrid cell. These abnormal cancer cells multiply over and over again, eventually taking over the bone marrow leading to a shortage of healthy blood cells in their body.

In WM, these cancer cells make abnormally large amounts of a specific antibody, called IgM. IgM is the largest of all the antibodies, called a macroglobulin. Usually, people have very low levels of IgM in their blood at any given time. With WM, you get high levels of IgM in your blood. Because of IgM’s large size and bulky structure, the blood becomes very thick. This is called hyperviscosity. Thick, or viscous blood, cannot flow easily through your body. This can lead to many of the symptoms associated with WM, including excess bleeding, vision problems, cardiovascular complications and nervous system issues.

What type of lymphoma is WM?

WM is a type of lymphoma called non-Hodgkin lymphoma. Non-Hodgkin lymphoma is not a single disease; it refers to a group of different cancers that start in the lymphocytes (white blood cells). WM is the most common form of one specific subtype of non-Hodgkin lymphoma.  That subtype is called lymphoplasmacytic lymphoma (LPL). WM cells are lymphoplasmacytic, meaning they have features of both plasma cells and lymphocyte cells.

WM is a slow-growing lymphoma and does not always require treatment. If you don’t have any symptoms, you do not need to be treated. If you do develop symptoms, treatment is needed.

While there is no cure for WM, there are different types of treatments that can lessen the symptoms and control the disease for many years.

History

Waldenstrom’s macroglobulinemia is named for the Swedish physician Jan Gosta Waldenström (1906-1996), who in 1944 identified a rare condition in which two patients experienced a thickening of their blood serum, bleeding of the mouth, nose, and blood vessels of the retina, low red blood cell and platelet counts, high erythrocyte sedimentation rates, and lymph node involvement. Bone marrow biopsies showed an excess of lymphoid cells and bone X-rays were normal, excluding a diagnosis of multiple myeloma. Both patients also had a large amount of a single unknown blood protein with an extremely high molecular weight, a “macro” globulin. We now know this globulin as IgM.

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